Japanese newspaper Nikkei said the deal could be worth over $30 billion

Japan's Softbank, the country's third-largest carrier, is in negotiations to acquire U.S. mobile operator Sprint in a deal worth over $30 billion, the Japanese business newspaper Nikkei reported Thursday.

The deal, in which Softbank would aim to buy all of the outstanding shares in Sprint, the third-largest carrier in the U.S., could be the largest purchase of a foreign company by a Japanese firm, the Nikkei said. Kyodo News Agency also reported Softbank was considering the deal, with neither news organization saying where the information came from.

Softbank released a statement on the reports Thursday evening Japan time.

"The story about SoftBank and Sprint Nextel Corporation being reported is based on speculation. We have not announced anything. We do not comment on speculation," the statement said.

Softbank is known to aggressively expand into new markets, and has large investments in Japan and Asia. The company said earlier this month it will purchase domestic rival eAccess in a $2 billion deal to help expand its mobile network.

The U.S. mobile industry is undergoing a wave of consolidation. Earlier this month, Deutsche Telekom's T-Mobile USA and MetroPCS Communications said they signed an agreement to merge in a deal that will see MetroPCS shareholders receive $1.5 billion in cash and 26 percent of the new company. T-Mobile is the fourth-largest U.S. mobile operator.

Sprint's chief financial officer said the company supported tie-ups in the mobile industry when asked about the MetroPCS deal Wednesday morning at a conference in Arizona.

"We aren't going to comment on the whole M&A thing," said CFO Joe Euteneuer, in response to a question. "We believe in consolidation in the industry, I don't think that has changed."